1. Field of the Invention
The present invention relates to chip removal devices for lathes. More particularly, the present invention relates to the use of high pressure coolant systems for the removal of chips from the interior bore of a workpiece affixed to a chuck of a lathe.
2. Description of the Prior Art
A lathe is a machine for revolving a piece of material so as to enable a cutting tool to shape it into a component of circular cross-section or to perform a screw-cutting operation. Lathes, which are among the most common machine tools, vary widely in design. What they have in common is that the workpiece is given a rotational movement and the material is cut away by a tool that is given an appropriate combination of linear (axial and radial) movements.
FIG. 1 shows a center lathe, also known as an engine lathe. This is the most widely used type of lathe. The lathe 10 has a chuck 12 which holds a workpiece 14 therein. The rotational movement is imparted to the workpiece 14 by the work spindle 16 mounted in the head stock 18 of the lathe 10. To enable long bars to be accommodated, the work spindle 16 may be of a hollow construction. The end of this spindle 16 is threaded to take various chucks, such as chuck 12. The chucks are gripping devices which hold the workpiece, as required. The required speed of rotation of the spindle 16, and therefore the cutting speed of the tool 20, is controlled by a suitable selection of the transmission ratio of the main gear box. Mounted on the guideways of the lathe""s bed 22 is the saddle (or carriage) 24. The saddle 24 carries the cutting tool 12 and is constructed as a compound slide. The saddle 24 moves in the longitudinal direction of the lathe 10. A cross slide 26 can be moved only in the transverse direction. Mounted on the cross slide 26 is the top slide 28. The top slide 28 can be moved longitudinally. It can also be swiveled about a vertical axis and clamped in any position as desired. The feed (advancing) and adjustment movements of the slides can be performed by means of crank handles on the saddle. Automatic control of the feed motion can be provided by means of the feed shaft, which receives its rotational movement from the work spindle 16. The feed shaft is provided with a worm which rotates with this shaft, but can slide longitudinally in relation to it.
At the opposite end of the lathe bed 22 from the head stock 18 is the tail stock 30. The tail stock 30 can move along the guideways and can be clamped in a desired position. The center sleeve in the tail stock can be moved in the longitudinal direction of the lathe 10 by means of a handwheel and screw spindle and can thus be brought toward the workpiece. The sleeve is provided with a tapered socket to take a center or a boring or reaming tool.
Threads are in widespread use as constructive elements in general mechanical engineering. These threads can be made in cylindrical or conical form. Chips are formed which correspond to the lead of such threads. These chips and shavings will wind up in a spiral configuration and be rather bulky. Usually, thread-cutting tools are equipped with the chip-breaker to prevent the formation of long continuous and bulky chips or shavings. Long, sharp and bulky chips or shavings are dangerous to the operator and cumbersome to handle. These chips will twist around the tool and cause damage to the cutting tool and workpiece. Chips or shavings broken by the chip-breaker are possibly treated safely and properly if they are formed during the external cutting process. However, if chips or shavings, which are broken by the chip-breaker, are formed during the internal cutting production, it is very difficult to remove them. They are pushed ahead by the cutting tool and stick inside the cylindrical or conical workpiece. In order to protect the cutting tool and workpiece against damage, the operator should stop the machine and remove them manually. This will result in less productivity. As a result, it is desirable to be able to remove the chips or shavings during the turning process. Such a system and device could be advantageous to the internal cutting production of parts.
During normal operations, the lathe operation must be stopped and the protective hood around the cutting operation must be opened. Conventionally, a worker will use a long rod to reach into the area within the interior of the workpiece so as to pull out the coiled chips. Subsequent to the removal of such chips, the rod must be removed, the protective door closed and the machining operation restarted. As can be understood, this is a very time consuming and labor-intensive process.
It is an object of the present invention to provide a method and apparatus for removing chips or shavings during the internal cutting production.
It is another object of the present invention to provide a method and apparatus for removing chips which allows the machining operation to be carried out on a continuous basis without interruption.
It is another object of the present invention to provide a method and apparatus for removing the chips or shavings during internal cutting production which protects the cutting tool and workpiece against damage.
It is still a further object of the present invention to provide a method and apparatus for removing chips which increases productivity and minimizes risk to the worker.
It is still a further object of the present invention to provide a method and apparatus for removing chips which is relatively inexpensive and easy to implement.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.
The present invention is a method and apparatus for removing chips from a lathe. As used herein, the term xe2x80x9cchipsxe2x80x9d includes chips, shavings, and other metal particles which are removed during the internal metal cutting operations of a lathe.
The apparatus of the present invention includes a spindle having a through hole formed therein, a chuck having a through hole formed therein affixed adjacent a forward end of the spindle such that the through hole of the chuck is aligned with the through hole of the spindle, a cutting mechanism cooperative with the chuck so as to remove metals from a workpiece mounted on the chuck, and a coolant line connected to the cutting mechanism and directed generally toward the through hole of the chuck so as to drive metal chips through the through hole of the spindle and outwardly of the rear end of the spindle.
In the preferred embodiment of the present invention, a guide sleeve is positioned within the through hole of the spindle. The guide sleeve is fixed and nonrotatable. The spindle will rotate around the guide sleeve. The guide sleeve will extend from the forward end toward the rearward end of the spindle. A tapered sleeve is affixed within the through hole of the chuck and extends toward the end of the guide sleeve adjacent to the forward end of the spindle. This tapered sleeve has a wide end opening at the through hole of the chuck and a narrow end adjacent to the forward end of the spindle. This tapered sleeve will rotate with the rotation of the spindle.
In the present invention, the cutting system includes a turret and a cutting tool affixed to a station of the turret. The coolant line is connected to the turret and extends toward the cutting tool. The coolant line has an outlet adjacent to the cutting tool. A chip removal tool is affixed to another station of the turret. The coolant line has another outlet at the chip removal tool. The turret is rotatable such that the chip removal tool can be positioned adjacent to the through hole of the chuck.
In the present invention, the coolant line includes a high pressure coolant line, a low pressure coolant line, a reservoir, and a pump means connected to the reservoir for pumping a liquid from the reservoir selectively through one of the high pressure coolant line and the low pressure coolant line. The pump means serves to pass liquid through an outlet of the high pressure coolant line at no less than 1,000 p.s.i. The pump means also serves to pass liquid through an outlet of the low pressure coolant line at between 100 and 1,000 p.s.i.
A chip conveyor is positioned so as to receive chips discharged from the rear end of the spindle.
The present invention is also a method of removing chips produced during the cutting operations of a lathe comprising: (1) forming a through hole in a spindle of the lathe; (2) attaching a coolant line adjacent a cutting tool of the lathe so as to have an outlet directed generally toward the through hole of the spindle; (3) pumping coolant through the coolant line such that the coolant line releases liquid at a pressure of no less than 100 p.s.i.; (4) cutting chips by the cutting tool from the workpiece affixed to the chuck; and (5) driving the chips through the through hole of the chuck and through the through hole of the spindle by the liquid pressure from the coolant line. The chips are discharged from an end of the spindle opposite the chuck.
The step of cutting the chips includes rotating the spindle. The method of the present invention also includes affixing a guide sleeve within the through hole of the spindle such that the guide sleeve is stationary during the rotation of the spindle. The step of affixing a coolant line includes affixing a high pressure coolant line adjacent to the cutting tool and affixing a low pressure coolant line adjacent to the cutting tool. The step of pumping includes pumping liquid at a pressure of greater than 1,000 p.s.i. through the high pressure coolant line. The step of pumping also includes pumping liquid at a pressure of between 100 and 1,000 p.s.i. through the low pressure coolant line.